Field of the Disclosure
The present disclosure is directed to medical fluid delivery applications and, particularly, to a magnetically-retained pressure jacket configured for use with a fluid injector.
Description of Related Art
In the medical field, patients often are injected with one or more medical fluids in various procedures. In such procedures, which require a controlled injection of a volume of one or more fluids into a patient, a needle is used as a conduit for the fluid and is connected to a syringe by a connector tube. One or more syringes may be mounted on a motorized fluid injector having one or more injector heads. In some embodiments, the fluid injector may have two injector heads capable of delivering distinct medical fluids from two separate syringes.
For long term compatibility with injectable fluids, syringes for use with the fluid injector may be made of polypropylene with a certain minimum wall thickness. Syringe thickness is an important design factor, as typical pressures of up to 1200 psi are used to inject the fluid into a patient. Pressure jackets are known in the art for enclosing and retaining syringes while in use. A pressure jacket serves to limit radial expansion of the syringe barrel due to fluid pressure during an injection procedure. Excessive radial expansion of the syringe may lead to bursting or to leaks of the pressurized fluid around the seals of the syringe plunger. During an injection procedure, an exterior wall of the syringe expands against an interior wall of the pressure jacket due to the extreme forces that act on the syringe in a radially outward direction. Additionally, the syringe and/or the pressure jacket may experience significant axial movement during a high pressure injection due to the elastic nature of the structural components restraining the syringe. For example, a force of 2400 pounds may be required to restrain the forward motion of a single 150 ml syringe with a cross-section of 1.6 in2 at 1200 psi. Such a force may result in as much as 0.100 inches of axial movement of the syringe and pressure jacket during the injection.
Certain present pressure jackets have a one-piece design, where the syringe is inserted into the pressure jacket from the front (distal) end of the pressure jacket. In these embodiments, the neck of the syringe protrudes from the front end of the pressure jacket such that the syringe may be connected to fluid lines leading to the patient. These pressure jackets are typically retained on the injector head by a coupling member that engages a groove circumscribing a proximal (rear) end of the pressure jacket.
However, such an arrangement is associated with a number of disadvantages. Fluid spilled during loading of the syringe and purging of air from the syringe may get inside the pressure jacket and the circumferential groove, thereby complicating the cleaning procedure. Because the pressure jacket is retained at the proximal (rear) end, it is subjected to high axial stress in the region of the circumferential groove during an injection procedure. Such axial stress can sometimes lead to slipping of the pressure jacket during the injection procedure, which may result in a loud and unsettling noise. In addition, continuous installation and removal of the pressure jacket from the injector head can cause significant wear on the circumferential groove.